(1) Field of the Invention
The invention is related to helicopters with engine air intakes, particularly to helicopters with radial engine air intakes with the features of the preamble of claim 1.
(2) Description of Related Art
Helicopters (HC) with lateral engine air inlet ports suck in the engine air from the side. In forward flight conditions of HC there will be air pressure losses with lateral engine air inlet ports, while for hover operations said lateral inlet ports are suitable. A ram-air intake is any intake design which uses the dynamic air pressure—so called RAM effect—created by vehicle motion to increase the static air pressure inside of the intake manifold on an engine, thus allowing a greater mass flow through the engine and hence increasing engine power.
The document US 2010/065139 A1 discloses a device for feeding combustion air to an engine disposed in an interior of an aircraft with an air inlet duct extending between an exterior surface of the aircraft and the engine, wherein the air inlet duct extends from air inlets disposed in a first region of the exterior surface; at least one further air inlet duct extending between a second region of the exterior surface and the engine, so as to provide a two-way airstream supply; and a control device configured to switch the air supply to the engine to the at least one further air inlet duct when a blockage occurs in the air inlets.
The document U.S. Pat. No. 5,662,292 A discloses a specially contoured barrier type filter disposed in front of a helicopter turbine inlet for maximized airflow during forward, as well as sideways flight. The contouring additionally reduces the tendency of the filter to clog. A bypass mechanism is provided should the pressure differential across the filter exceed a predetermined value. The bypass configuration achieves a limited particle separation function in order to provide residual protection. An air box attached to the inlet is formed to provide low distortion levels in the airflow entering the engine inlet.